Yes, get registered asap.
But, I don't think you need to be registered to post a link. you just need to know how to input a link in html:

[a href="http://domain.extension"]link text[/a]

just replace the [ , ] with < , > and it will look like this:
link text   http://domain.extension  

to test, I will post a reply with an unregistered nick and the same link as above.

In Christ,